JP3656444B2 - Eddy current reducer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an eddy current reduction device in which processing of a guide tube and coupling of a ferromagnetic plate to the guide tube are simple.
[0002]
[Prior art]
A movable magnet support tube and an immobile magnet support tube are accommodated in an inner space of a rectangular cross section of the guide tube disposed inside the brake drum, and the movable magnet support tube is rotated forward and backward to rotate each magnet support tube. In a conventional eddy current reduction device that switches between a non-braking position in which the polarities of axially aligned magnets (permanent magnets, hereinafter the same) coupled to the outer peripheral surface are different and a braking position in which the polarities of magnets aligned in the axial direction are the same, Sometimes a fairly thick ferromagnetic plate (usually 10-16 mm) must be embedded in the guide cylinder facing the inner peripheral surface of the brake drum so that the magnetic field of the magnet does not reach the brake drum. For this reason, a ferromagnetic plate is cast into a guide tube made of cast aluminum, or a large number of openings are provided in a guide tube press-formed from a non-magnetic stainless steel plate, and each plate is fitted with a ferromagnetic plate and welded. ing. The former method has a low yield, and the latter method requires a lot of processing, and it is difficult to reduce the cost of both methods.
[0003]
[Problems to be solved by the invention]
In view of the above-described problems, an object of the present invention is to provide an eddy current reduction device that is easy to process a guide tube and is useful for weight reduction and cost reduction.
[0004]
[Means for Solving the Problems]
In order to solve the above problems, the configuration of the present invention includes a brake drum coupled to a rotating shaft, at least one movable magnet support cylinder inside the brake drum, and an outer peripheral surface of the movable magnet support cylinder. An eddy current reduction device for generating a braking force on a braking drum by an eddy current based on a magnetic field from the magnet, and a thin plate of soft magnetic material on the outer peripheral side of the magnet And a ferromagnetic plate facing each magnet is coupled to one of the inner and outer peripheral surfaces of the guide cylinder.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, a thick ferromagnetic plate is coupled by welding to a portion of the guide cylinder made of a thin plate of soft magnetic material facing the magnet, and the guide cylinder is arranged on the outer peripheral side of the magnet. The portion of the guide tube between the ferromagnetic plate and the ferromagnetic plate (between the magnets) may be thin so that the magnetic field is not easily transmitted. In order to secure the rigidity of the guide tube, a reinforcing plate made of a nonmagnetic material such as aluminum or stainless steel may be joined to the thin portion by welding, brazing, or the like.
[0006]
In order to make the eddy current easily flow through the brake drum, an annular body made of a good conductor such as copper is coupled to a portion of the brake drum not facing the ferromagnetic plate.
[0007]
【Example】
As shown in FIG. 1, an eddy current reduction device according to the present invention includes a flange 5a of a boss portion 5 of a brake drum 8, a parking brake, a mounting flange 3 that is spline-fitted to an output rotary shaft 2 of a vehicle transmission, for example. The brake drum 4 end wall plate is fastened together by a plurality of bolts 6 and nuts. A base end portion or a right end portion of a brake drum 8 having a large number of cooling fins 9 on the outer peripheral surface is coupled to the distal ends of a large number of support arms 7 protruding radially outward from the boss portion 5 by welding or the like. An annular plate 10 made of a good conductor such as copper is coupled to the end wall surface of the open end portion or the left end portion of the brake drum 8, and an annular plate is formed on the left end portion not facing the ferromagnetic plate 41 on the inner peripheral surface of the brake drum 8. A cylindrical or annular plate 11 integrated with the plate 10 is coupled. A similar cylinder or annular plate 12 is also coupled to the right end portion of the inner peripheral surface of the brake drum 8 that does not face the ferromagnetic plate 41. Each of the annular plates 10 to 12 has an axial spread of the eddy current flowing inside the brake drum 8 and increases the braking torque.
[0008]
Inside the brake drum 8, a guide cylinder 21 having an inner space with a rectangular cross section is disposed. The guide tube 21 is formed by connecting a cylindrical portion having an L-shaped cross section having a side wall 24 made of a nonmagnetic material and an inner guide tube 23 and a side wall 24a made of a nonmagnetic material annular plate by a plurality of bolts. Both side edges 20 of the outer guide tube 22 formed from a thin plate are bent radially inward and fixed to the side walls 24, 24a. A large number of block-shaped ferromagnetic plates (pole pieces) 41 are coupled to the outer peripheral surface of the outer guide cylinder 22 at equal intervals in the circumferential direction so as to face the inner peripheral surface of the brake drum 8.
[0009]
A movable magnet support cylinder 25 and a stationary magnet support cylinder 26 made of a magnetic material are accommodated in the inner space of the guide cylinder 21. The movable magnet support tube 25 is supported by the inner guide tube 23 by a bearing 25a so as to be rotatable forward and backward, and the magnet support tube 26 is fixed to the inner guide tube 23 by a bolt or the like. A large number of magnets 15 and 16 facing each ferromagnetic plate 41 are arranged at equal intervals in the circumferential direction on the outer peripheral surfaces of the magnet support cylinders 25 and 26, and the polarities facing the ferromagnetic plates 41 are alternately different in the circumferential direction. Combined with
[0010]
A fluid pressure actuator 31 for rotating the movable magnet support cylinder 25 in the forward and reverse directions is formed by inserting a piston 33 into a cylinder 32 formed integrally with the side wall 24 so as to define both end chambers, and outside the rod connected to the piston 33. The end is connected to the arm 34 protruding from the magnet support cylinder 25 through the slit 35 on the side wall 24 to the outside.
[0011]
In the eddy current reduction device described above, when not braked, the magnet 15 of the magnet support tube 25 and the magnet 16 of the magnet support tube 26 arranged in the axial direction have opposite polarities with respect to the ferromagnetic plate 41, and the magnet support A short-circuit magnetic circuit z is generated between the cylinders 25 and 26 and the ferromagnetic plate 41. Therefore, since the magnetic fields of the magnets 15 and 16 do not reach the braking drum 8, no braking torque is generated in the braking drum 8. At the time of braking, when the magnet support cylinder 25 is rotated by the arrangement pitch of the magnets 15 by the actuator 31, the polarities of the magnets 15 and 16 of the magnet support cylinders 25 and 26 with respect to the ferromagnetic plate 41 become the same. Therefore, when the braking drum 8 that rotates the magnetic field from the magnets 15 and 16 crosses, a braking torque based on the eddy current is generated in the braking drum 8. At this time, as shown in FIG. 2, a magnetic circuit w is generated between the brake drum 8 and the magnet support cylinders 25 and 26.
[0012]
However, in actuality, during the high speed rotation of the brake drum 8, the magnetic circuit w looks like it is dragged in the rotation direction indicated by the arrow x of the brake drum 8. The cross-sectional shape is preferably a shape as shown in FIGS. 9 and 10 rather than a rectangular shape, and the shape as shown in FIG.
[0013]
As shown in FIG. 2, the magnets 15 and 16 are superimposed on the outer peripheral surfaces of the magnet support cylinders 25 and 26, and the magnets 15 and 16 are sandwiched between the magnets 15 and 16 adjacent in the circumferential direction. , 16 are overlapped on shoulders 15a formed on the front and rear end walls, and are fastened to support cylinders 25, 26 by a plurality of bolts 28, respectively.
[0014]
As shown in FIG. 3, by forming an axial groove in a portion between the ferromagnetic plates 41 on the inner peripheral surface of the outer guide tube 22 made of a thin soft magnetic plate, the thin portion 42 is formed. It is possible to suppress the occurrence of a short circuit magnetic circuit due to a leakage magnetic field between the outer guide tube 22 and the magnet support tube 25. In order to reinforce the thin portion 42 of the outer guide tube 22, it is preferable that a reinforcing plate 43 made of a non-magnetic material is joined to the outer guide tube 22 by welding, brazing or the like so as to cover the axial groove. In the embodiment shown in FIG. 4, the rigidity strength of the outer guide tube 22 can be further increased by connecting the reinforcing plate 44 having a groove section.
[0015]
As shown in FIG. 5, an axial groove is provided on the outer peripheral surface of the outer guide tube 22 to form a thin portion 42, and a cross-sectional groove-type reinforcing plate 45 is engaged with the axial groove so that the reinforcing plate 45 If the front and rear edges are engaged with the ferromagnetic plates 41 arranged in the circumferential direction, the positioning of the ferromagnetic plates 41 in the circumferential direction is facilitated.
[0016]
In the embodiment shown in FIG. 6, contrary to the embodiment shown in FIG. 5, a ferromagnetic plate 41 is joined to the inner peripheral surface of the outer guide tube 22 by welding, and a groove is formed on the inner peripheral surface of the outer guide tube 22. The thin-walled portion 53 is formed between the ferromagnetic plate 41 and the ferromagnetic plate 41, and the reinforcing plate 45 having a cross-sectional groove shape is engaged with the groove. Is engaged with the rear front end face.
[0017]
In the embodiment shown in FIG. 7, the outer guide cylinder 22 is composed of a pair of inner and outer cylinders 22a and 22b made of a soft magnetic plate having thin portions 53 and 42, respectively, and the ferromagnetic plate 41 is interposed between the cylinders 22a and 22b. And the coupling strength of the ferromagnetic plate 41 to the outer guide tube 22 can be increased.
[0018]
In each of the embodiments described above, the ferromagnetic plate 41 has a block shape. However, the present invention is not limited to this, and an outer surface 46 and an inner surface 47 that form a cylindrical surface as shown in FIGS. 8 is coupled to the outer guide tube 22, and in the embodiment shown in FIG. 8, the outer peripheral side of the front end surface (the front end surface in the rotational direction of the braking drum 8) 48 is cut away to form an inclined surface 48a. Similarly, by cutting off the outer peripheral side of the rear end surface 49 to form the inclined surface 49a, the magnetic flux from the magnets 15 and 16 is narrowed (increase the magnetic flux density) and led to the braking drum 8 to increase the braking torque. Can do. In the embodiment shown in FIG. 9, the front end face 48 and the rear end face 49 are inclined in the rotational direction indicated by the arrow x in FIG. The magnetic fluxes from the magnets 15 and 16 can be narrowed down to the front end of the ferromagnetic plate 41 (the rotation direction of the braking drum 8). In the embodiment shown in FIG. 10, the rear half portion of the outer surface 46 of the ferromagnetic plate 41 is cut to form a stepped portion 46a, and the magnetic flux from the magnets 15 and 16 is transferred by the high speed rotation of the brake drum 8 to the ferromagnetic plate. It is possible to further narrow down the front end portion of 41 and apply it to the braking drum 8.
[0019]
In the embodiment shown above, the movable magnet support tube 25 and the stationary magnet support tube 26 are accommodated in the inner space of the guide tube 21, but the movable magnet support tube 25 is disposed in the inner space of the guide tube 21. The present invention can also be applied to an eddy current reduction device that accommodates only. At the time of non-braking, the magnet support cylinder 25 is rotated by the half arrangement pitch of the magnet 15 from the braking position shown in FIG. 2, and two magnets having different polarities arranged in the circumferential direction partially face the common ferromagnetic plate 41. By doing so, a short-circuit magnetic circuit is generated between the magnet support cylinder 25 sandwiching the inner and outer surfaces of the two magnets 15 and the ferromagnetic plate 41, and no magnetic field is applied to the braking drum 8.
[0020]
As shown in FIG. 11, the present invention is an eddy current type in which the magnet support cylinder 25 is switched between a braking position where the fluid pressure actuator 31 is pushed into the braking drum 8 and a non-braking position pulled out from the braking drum 8. It can also be applied to a reduction gear. The guide tube 21 includes an outer guide tube 19 made of a magnetic material, a side wall 24 and a cylindrical portion having a C-shaped cross section having an inner guide tube 23, an outer guide tube 22 made of the aforementioned soft magnetic plate, and a side wall 24a made of a non-magnetic material. Are combined to form an inner space 21a having a rectangular cross section. A large number of ferromagnetic plates 41 are coupled to the inner peripheral surface of the outer guide tube 22 at equal intervals in the circumferential direction. A magnet support cylinder 25 that supports the magnet 15 facing each ferromagnetic plate 41 is accommodated in the inner space 21a. The magnet support cylinder 25 is supported along the inner guide cylinder 23 so as to be able to reciprocate. A rod 34 a extending from the piston 33 of the fluid pressure actuator 31 through the side wall 24 to the inner space 21 a is coupled to the magnet support cylinder 25. However, the coupling between the outer guide tube 22 and the ferromagnetic plate 41 can be configured as shown in FIGS. The fluid pressure actuator 31 is different from that shown in FIG. 1 in that a cylinder 32 is disposed in the axial direction of the brake drum 8 and an end wall is coupled to the side wall 24. The brake drum 8 is the same as that shown in FIG.
[0021]
When the magnet support cylinder 25 is pulled out of the braking drum 8 from the braking position shown in FIG. 11 during non-braking, the magnet 15 forms a short circuit magnetic circuit between the outer guide cylinder 19 and the magnet support cylinder 25, and braking is performed. A magnetic field does not reach the drum 8.
[0022]
【The invention's effect】
In the present invention, as described above, the brake drum coupled to the rotating shaft, at least one movable magnet support cylinder inside the brake drum, and the outer peripheral surface of the movable magnet support cylinder are coupled at equal intervals. In an eddy current reduction device that generates a braking force on a braking drum by an eddy current based on a magnetic field from the magnet, a guide tube made of a thin plate of soft magnetic material is installed on the outer peripheral side of the magnet Since the ferromagnetic plate is coupled to one of the inner and outer peripheral surfaces of the guide cylinder so as to face each magnet, the outer guide cylinder supporting the ferromagnetic plate can be formed by press molding, and the ferromagnetic plate is welded. Since it can be joined by brazing, etc., it is easy to process, and the yield is better than the conventional example in which a ferromagnetic plate is cast into an outer guide tube such as aluminum, and the processing cost can be reduced. High bond strength can be obtained.
[Brief description of the drawings]
FIG. 1 is a front sectional view of an eddy current reduction device according to the present invention.
FIG. 2 is a side sectional view showing a main part of the eddy current reduction device.
FIG. 3 is a side sectional view showing a partially modified embodiment of the eddy current reduction device.
FIG. 4 is a side sectional view showing a partially modified embodiment of the eddy current reduction device.
FIG. 5 is a side sectional view showing a partially modified embodiment of the eddy current reduction device.
FIG. 6 is a side sectional view of an eddy current reduction device according to a second embodiment of the present invention.
FIG. 7 is a side sectional view of an eddy current reduction device according to a third embodiment of the present invention.
FIG. 8 is a side view showing a cross-sectional shape of a ferromagnetic material.
FIG. 9 is a side view showing a cross-sectional shape of a ferromagnetic material.
FIG. 10 is a side view showing a cross-sectional shape of a ferromagnetic material.
FIG. 11 is a front sectional view showing another type of eddy current reduction device to which the present invention is applied.
[Explanation of symbols]
2: Rotating shaft 5: Boss portion 7: Support arm 8: Braking drum 10: Annular plate of good conductor 11: Annular plate of good conductor 12: Annular plate of good conductor 15: Magnet 16: Magnet 21: Guide tube 22: Outer guide tube 22a: Tube body 22b: Tube body 23: Inner guide tube 24: Side wall 24a: Side wall 25: Magnet support tube 26: Magnet support tube 29: Holder 31: Fluid pressure actuator 35: Slit 41: Ferromagnetic Plate 42: Thin portion 43: Reinforcement plate 44: Reinforcement plate 45: Reinforcement plate 53: Thin wall portion 54: Reinforcement plate

Claims (6)

A brake drum coupled to the rotating shaft, at least one movable magnet support cylinder inside the brake drum, and a number of magnets coupled at equal intervals to the outer peripheral surface of the movable magnet support cylinder; In the eddy current reduction device for generating a braking force on the braking drum by an eddy current based on the magnetic field from the magnet, a guide cylinder made of a thin soft magnetic material is installed on the outer peripheral side of the magnet, and the inner and outer periphery of the guide cylinder An eddy current reduction device characterized in that a ferromagnetic plate facing each magnet is coupled to one of the surfaces. A brake drum coupled to the rotating shaft, at least one movable magnet support cylinder inside the brake drum, and a plurality of magnets coupled at equal intervals to the outer peripheral surface of the movable magnet support cylinder; In an eddy current reduction device for generating a braking force on a braking drum by an eddy current based on a magnetic field from the magnet, two guide cylinders made of a soft magnetic thin plate are installed on the outer peripheral side of the magnet, and the two inner and outer guide cylinders are installed. An eddy current reduction device characterized in that a ferromagnetic plate facing each magnet is interposed between guide cylinders. The eddy current reduction device according to claim 1, further comprising a thin portion between magnets adjacent to each other in the circumferential direction of the guide tube. The eddy current reduction device according to claim 3, wherein a reinforcing plate made of a non-magnetic material is coupled to the thin portion of the guide tube. The eddy current reduction device according to claim 1, wherein an area of the outer surface of the ferromagnetic plate is narrower than an area of the inner surface. The eddy current moderator according to any one of claims 1 and 2, wherein an annular body made of a good conductor such as copper is coupled to at least one end portion of the inner peripheral surface of the brake drum that does not face the ferromagnetic plate. apparatus.

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